The present invention relates to a direct coupled motor-driven vehicle, and in particular, to an air-conditioning system and method for a direct coupled motor-driven hybrid electric vehicle.
Typically, a direct coupled motor-driven vehicle has a powertrain system such that a motor is interconnected between an engine and a transmission. This motor is used for starting and driving the vehicle, and as a generator.
Conventional parallel hybrid electric vehicles and direct coupled type 42V vehicles typically utilize conventional air conditioning systems. Such conventional air conditioning systems require torque from the engine to operate. Therefore, when the air conditioning system is activated, the engine must be running. This is inefficient. Also, when the engine rpm is low in a vehicle equipped with a conventional air conditioning system, the rpm of the compressor is also low, thereby degrading the cooling performance of the air conditioning system. Furthermore, in conventional air conditioning systems, the compressor uses engine torque such that the operating performance of the vehicle is degraded, particularly when accelerating or when the vehicle is driving up an incline.
In a preferred embodiment of the present invention, the method for controlling a hybrid air conditioning system of a direct coupled motor driven hybrid electric vehicle comprises: detecting operating conditions of the hybrid air conditioning system and controlling the hybrid air conditioning system. The hybrid air conditioning system includes a mechanical air conditioner driven by an engine and an electric air conditioner driven by electric power of a battery.
It is preferable that detecting operating conditions of the air conditioning system includes: detecting an on/off state of an air conditioning system switch; calculating a temperature difference between a detected interior temperature and a target temperature if the air conditioning system switch is on; and detecting operating condition of the vehicle. Preferably, the detecting an operating condition of the vehicle includes determining whether or not the engine is in an idle stop state and determining whether or not a state-of-charge of a battery is greater than a predetermined value when the engine is in the idle stop state. The controlling the air conditioning system includes stopping operation of the mechanical air conditioner when the state-of-charge of the battery is greater than a predetermined value and starting operation of the electric air conditioner when a refrigerant temperature in an evaporator of the electric air conditioner is greater than a predetermined temperature.
It is further preferable that the detecting an operating condition of the vehicle includes: determining whether or not the engine is in an idle stop state; determining whether or not a state-of-charge of a battery is greater than a predetermined value when the engine is in the idle stop state; and restarting the engine when the state-of-charge of the battery is below the predetermined value. The controlling the air conditioning system includes: stopping operation of the mechanical air conditioner when the vehicle suddenly accelerates and starting operation of the electric air conditioner when a refrigerant temperature in an evaporator of the electric air conditioner is greater than a predetermined temperature.
Preferably, the detecting an operating condition of the vehicle includes: determining whether or not the engine is in a state of idle stop; and determining whether or not the vehicle is suddenly accelerating, when the engine is not in the idle stop state. The controlling the air conditioning system includes: stopping operation of a mechanical air conditioner and starting operation of the electric air conditioner if a refrigerant temperature in an evaporator of the electric air conditioner is greater than a predetermined temperature, when the vehicle suddenly accelerates.
It is further preferable that the detecting an operating condition of the vehicle includes: determining whether or not the engine is in an idle stop state; and determining whether or not the vehicle suddenly accelerates, when the engine is not in the state of idle stop. The controlling the air conditioning system includes: starting operation of the mechanical air conditioner when a refrigerant temperature in an evaporator of the mechanical air conditioner is greater than a predetermined temperature, and starting operation of the electrical air conditioner when a refrigerant temperature in an evaporator of the electric air conditioner is greater than a predetermined temperature, in the case that the vehicle is not suddenly accelerating.
Preferably, the detecting an operating condition of the vehicle includes: determining whether or not the engine is in an idle stop state; and determining whether or not a state-of-charge of a battery is greater than a predetermined value when the engine is in the idle stop state; restarting the engine when the state-of-charge of the battery is below the predetermined value; and determining whether or not the vehicle is suddenly accelerating when the engine is restarted. The controlling the air conditioning system includes: starting operation of the mechanical air conditioner when a refrigerant temperature in an evaporator of the mechanical air conditioner is greater than a predetermined temperature and starting operation of the electrical air conditioner when a refrigerant temperature in an evaporator of the electric air conditioner is greater than a predetermined temperature, in a case that the vehicle is suddenly accelerating.
In another preferred embodiment of the present invention, the hybrid air conditioning system of a direct coupled motor driven hybrid electric vehicle includes an operating condition detector, an electric air conditioner, a mechanical air conditioner, and a control unit. The operating condition detector detects at least one operating condition of the hybrid air conditioning system. The electric air conditioner is driven by electric power of a battery, and the mechanical air conditioner is driven by an engine. The control unit controls the hybrid air conditioning system based on the operating condition inputted from the operating condition detector.
It is preferable that the operating condition detector includes an air conditioning system switch, an interior temperature detector, an engine rpm detector, a battery status detector, a first evaporator refrigerant temperature detector, and a second evaporator refrigerant temperature detector. The air conditioning system switch turns the hybrid air conditioning unit on and off. The interior temperature detector detects temperature inside the vehicle. The engine rpm detector detects engine rpm. The battery status detector detects state-of-charge (SOC) of the battery. The first evaporator refrigerant temperature detector detects refrigerant temperature in an evaporator of the mechanical air conditioner. The second evaporator refrigerant temperature detector detects refrigerant temperature in an evaporator of the electrical air conditioner.
It is further preferable that the mechanical air conditioner includes a mechanical compressor, a condenser, an expansion valve, an evaporator, and a blower unit. The mechanical compressor compresses the refrigerant using mechanical power from the engine. The condenser condenses the refrigerant from the mechanical compressor by radiating heat of the refrigerant. The expansion valve expands the refrigerant from the condenser. The evaporator vaporizes the refrigerant by absorbing heat from outside. The blower unit blows air refrigerated around the evaporator into target space.
It is also preferable that the electric air conditioner includes an electrical compressor, a condenser, an expansion valve, an evaporator, and a blower unit. The electrical compressor compresses the refrigerant using electric power of a battery. The condenser condenses the refrigerant from the electrical compressor by radiating heat of the refrigerant. The expansion valve expands the refrigerant from the condenser. The evaporator vaporizes the refrigerant by absorbing heat from outside. The blower unit blows air refrigerated around the evaporator into a target space.